The title complex {[Cu₂(dhbd)(bipy)₂]•10H₂O}_n (H₄dhbd＝2,3-dihydroxybutanedioate tetraanion, bipy＝2,2′-bipyridine) has been hydrothermally synthesized and characterized by means of elemental analysis, IR, TG-DSC and single crystal X-ray diffraction. The results show that the complex is monoclinic, with space group C2/c, a＝2.1965(4) nm, b＝1.0671(2) nm, c＝1.3662(3) nm, β＝93.50(3)°, Z＝4 and R＝0.0388. The crystal structure of complex consists of a U-shaped binuclear unit with C₂ axis and ten water molecules, in which the U-shaped unit is made of two Cu(II) nuclei with one tetraanionic dhbd adopting bis didentate coordination mode and two 2,2'-bipy ligands, moreover, two coordination carboxy O atoms of dhbd group bridge the two neighboring reversed U-shaped frame to form a 1-D polymeric chain along the crystallographic axis c．These coordination polymer chains are further organized by two different intermolecular hydrogen bonds (C—H…O and O—H…O) to afford a 3D supramolecular structure. This binding mode of dhbd group was not observed so far．

Key words: copper(II) dihydroxybutanedioate, polymeric complex, coordination mode, hydrothermal synthesis, crystal structure